This invention relates to a toy which repeatedly turns itself upside down and then rolls upon a curved surface incorporated in the toy from its uprighted position back to its upright position.
Toys are known which have a rounded outside surface and are weighted or otherwise constructed such that their center of gravity is located below the center of rotation of the rounded surface. If this type of toy is placed upside down it will, because the center of gravity is lower than the radius of curvature, roll about its curved surface until it comes to rest in an upright position wherein the center of gravity is again located below the radius of curvature. These toys, however, do not have the ability to invert themselves but must be physically inverted by the user of the toy.
A second type of toy is known which has the ability to upset itself. This type of toy uses a mechanism wherein the toy is steered by two wheels whose axle is pivotally mounted to the toy via pivots which are displaced about a wheel's radius to the rear of the axle. Depending upon the exact distance of this rearward displacement of the pivots and a particular velocity of the vehicle it is possible for this vehicle to spontaneously have its front steering wheels fully displaced either to the left or right causing the vehicle to upset itself about its front wheels. While this mechanism is very interesting and of considerable play value, because of the necessary tuning of the vehicle velocity with steering component dimensions, the vehicle may not always upset itself. Once the before described vehicle has upset itself it has the ability to right itself through a combination of a projection projecting downward from the body and an oversized winding key attached to its spring motor. The winding key lifts the side of the vehicle up until it is once again resting on its wheels.
A different type of toy vehicle has the ability to do "wheelies". This toy vehicle has a fifth wheel which is mounted on a lever. The lever is pivotally mounted to the vehicle near the vehicles front wheels and then extends toward the rear of the vehicle placing the fifth wheel somewhere toward the center of the vehicle. When the lever is activated or rotated about its fulcrum the fifth wheel descends downward causing the front end of the vehicle to be raised. This type of mechanism, however, is not useful to completely upset a vehicle because of the location of the fulcrum point of the lever. Because the lever is pivoted to the front of the vehicle, but the vehicle itself pivots about the rear wheels, it is never possible to lift the front end of the vehicle a sufficient height to cause the vehicle to rotate about its axles and flip over.
In U.S. Pat. No. 3,728,815, assigned to the same assignee as this patent, there is described a toy which travels on a horizontal surface. The arms of this toy rotate about attachment points and if the toy is confronted with a vertical surface the rotating arms contact the vertical surface, upset the toy and then further flip the toy about its head until it is again uprighted.
From the above descriptions of known toys it is evident that there is considerable play value in constructing a toy which combines an upsetting or righting movement in combination with the normal rolling movement of the toy. None of the toys described, however, have the ability to repeatedly upset themselves while traveling on strictly a horizontal surface, and while traveling at a variable velocity, i.e. whatever momentary velocity their fully or partially wound spring motors may propel them at as the spring tension is released.